Although the State-Trait Anxiety Inventory (STAI) is a popular measure of anxiety, some previous research suggests that the trait scale may assess depression, as well as anxiety. The factor structure of the trait items was initially examined using factor analytic procedures. Confirmatory factor analytic methods suggested that a hierarchical solution best fit the data, with one overall factor and two lower order factors. The lower order subscales created from this factor solution were examined in a sample of individuals diagnosed with an anxiety disorder. Overall, the results offered good support for the notion that the trait scale of the STAI assesses depression, as well as anxiety. One set of items appeared to assess anxiety and worry, whereas the other assessed sadness and self-deprecation. The two subscales correlated differentially with other measures of anxiety and depression in a manner that was consistent with their content. Finally, diagnostic groups and controls could be meaningfully distinguished on these subscales. Implications for the use of this measure are discussed.